rneubig

Too much regen in D mode

Mon Aug 14, 2017 2:45 am

I just switched from Volt to Bolt - yesterday. I love the car so far and am excited about the range.

One disappointing thing is that you can't coast easily in D mode like you can in the Volt. I'd rather use my momentum to keep going rather than having the car slow when I let off the accelerator then have to speed back up again. It is obviously more efficient to avoid the change from kinetic to battery energy then back again. Plus it is more enjoyable to me to have the smooth coast.

By using the brake very judiciously, I can usually get all the regen I want by slowing well before the red light or stop sign. If I time it right, I don't need to use either the brake or the accelerator which is most efficient.

Is there any way to turn off the regen in D mode? That would seem to be a simple thing to give as an option.

Thanks,

GernBlanston
Posts: 94
Joined: Sat Jun 24, 2017 12:28 am

Re: Too much regen in D mode

Mon Aug 14, 2017 3:38 am

You just have to feather it.
Just let off enough to 'coast'.
You'll get used to it.
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PV1
Posts: 38
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Re: Too much regen in D mode

Mon Aug 14, 2017 1:26 pm

How long do you usually coast? It's easy to slip into Neutral and truly coast when you want. Hold the shifter forward for a second. To go back to Drive, just click it back.

Just be aware that you have to go back into Drive to get power or regen.
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redpoint5
Posts: 76
Joined: Tue Apr 04, 2017 5:17 am

Re: Too much regen in D mode

Mon Aug 14, 2017 4:04 pm

I'm annoyed that almost all manufacturers feel the need to carry over this useless behavior. As the lead engineer for the Bolt said, they wanted the car to slow at a rate that is similar to what drivers had experienced in other (automatic) vehicles.

As many of us know, the slowing of an automatic car is not a designed feature, but rather a consequence of how torque converters work. Manual (used to be called standard) transmission cars have a true coast whenever the clutch is pushed. Another annoying "feature" is that the car creeps forward when releasing the brake in D mode. Again, vehicle creep isn't something that was designed in, but rather a consequence of how a torque converter works in an automatic transmission. Manually shifted vehicles don't creep.

My Prius also has no way to bypass regen when letting off the accelerator. Feathering the pedal is tricky because it's impossible to get it exactly right. You will always either be supplying some power, or regenerating some amount. I've grown accustomed to shifting to neutral to coast, and then putting it back in D just before slowing down with regen.

The real shame is that it would cost nothing to make these 2 antiquated behaviors optional to the driver, except for the increased incidence old people bringing their car to the dealership not realizing the setting they had inadvertently set.

sgt1372
Posts: 533
Joined: Mon Feb 06, 2017 4:21 pm
Location: SF Bay Area

Re: Too much regen in D mode

Mon Aug 14, 2017 6:10 pm

LOL!

I think that D modes doesn't have enough regen effect and don't like the way it continues to roll after I release the accelerator. So, I just drive it L mode all the time. Accelerates and decels much more predictably and efficiently for me in this way

Funny how we all want/like different things.
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Pigwich
Posts: 240
Joined: Tue Jan 03, 2017 2:01 pm
Location: Southern California

Re: Too much regen in D mode

Mon Aug 14, 2017 6:22 pm

redpoint5 wrote:I'm annoyed that almost all manufacturers feel the need to carry over this useless behavior. As the lead engineer for the Bolt said, they wanted the car to slow at a rate that is similar to what drivers had experienced in other (automatic) vehicles.


I'm on the fence here - I completely see your point, and you make a great argument, and nothing you say is false in any way, BUT literally everybody in the world is used to a certain behavior, and to have to re-train everybody is daunting. When somebody hops in a car, if it acts "funny" they don't want to drive it. I can appreciate it being an option, but again, you're 100% right on the service calls that would be generated.

There's also an argument to be made for safety, and I think this may be the biggest one, going back to what people are "used to" and that is they're used to a certain amount of slowing down when they let their foot off the throttle. If the car keeps coasting, it might be a surprise. I drove a gas car for 20 years before my first EV - That's a lot of muscle memory to get rid of.

On the other hand, and completely counter to your opinion is that there isn't ENOUGH regen when you lift off the pedal. I drive in god-awful traffic every day, thankfully only for a few miles, but the argument can be made, and I will make it, that the extra 300 milliseconds of deceleration you get when driving in L when you go from throttle to brake might make the difference between a fender bender and a close call.

Ultimately, however, it's up to the driver as to what kind of behavior they want. More and more people are enjoying one-pedal driving in EVs, which is MORE regeneration, but it does take some time getting used to it. I take a lot of people for test drives in my car, and L drives them crazy at first. But driving driving in L has it's own safety concerns. A good one can be made regarding people NOT holding their foot on the brake when they come to a complete stop with one pedal driving. This is a problem, since a car struck from the rear can more easily be pushed into the path of traffic with deadly consequences.

Your call, as a driver, it it could be a choice but as far as I can see, you're facing an uphill battle for popularity of this feature.

Maybe some hacker type person can find out which PID it is that needs to get changed and they can help you out?
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NeilBlanchard
Posts: 337
Joined: Tue May 31, 2016 4:58 pm
Location: Massachusetts

Re: Too much regen in D mode

Mon Aug 14, 2017 8:12 pm

I agree with redpoint5 - we need an option for free wheel coasting in D. It should be the default, but it should be the driver's choice, at least.

The e-Golf and the Ioniq EV have coasting, and it is the most efficient. But, for the moment, like the Leaf, I will be shifting it into neutral.

redpoint5
Posts: 76
Joined: Tue Apr 04, 2017 5:17 am

Re: Too much regen in D mode

Mon Aug 14, 2017 8:24 pm

Pigwich wrote:
redpoint5 wrote:I'm annoyed that almost all manufacturers feel the need to carry over this useless behavior. As the lead engineer for the Bolt said, they wanted the car to slow at a rate that is similar to what drivers had experienced in other (automatic) vehicles.


I'm on the fence here - I completely see your point, and you make a great argument, and nothing you say is false in any way, BUT literally everybody in the world is used to a certain behavior, and to have to re-train everybody is daunting. When somebody hops in a car, if it acts "funny" they don't want to drive it. I can appreciate it being an option, but again, you're 100% right on the service calls that would be generated.

There's also an argument to be made for safety, and I think this may be the biggest one, going back to what people are "used to" and that is they're used to a certain amount of slowing down when they let their foot off the throttle. If the car keeps coasting, it might be a surprise. I drove a gas car for 20 years before my first EV - That's a lot of muscle memory to get rid of.


But drivers had to learn to get used to the slight deceleration and creep introduced with automatic transmissions. I can't see the lack of slight deceleration causing a safety concern, and I certainly see a huge safety issue with allowing a vehicle to creep without any driver input. I've been driving for almost 20 years myself, and I'm used to coasting with the clutch in, and no creep from a manual transmission. I'm in the minority in the US, but manual transmissions are still popular in many places around the world.

On the other hand, and completely counter to your opinion is that there isn't ENOUGH regen when you lift off the pedal. I drive in god-awful traffic every day, thankfully only for a few miles, but the argument can be made, and I will make it, that the extra 300 milliseconds of deceleration you get when driving in L when you go from throttle to brake might make the difference between a fender bender and a close call.


I was considering whether the instant braking from letting off the accelerator would prevent more accidents, or train people to be unfamiliar with the brake pedal when they really need to emergency brake. I'll be curious to see how this one plays out as 1-pedal driving becomes more common.

As the OP mentioned, it's way more efficient to drive in D mode and coast down than it is to regen. Almost everyone drives bumper to bumper though, and in that case it's more efficient to regen than use friction brakes.

I actually get better fuel economy in gridlocked Portland traffic in my manual transmission car than highway driving. The reason is that I drive the average speed of traffic, allowing a gap to form when people are racing ahead to the next slowdown, and shrinking the gap as I approach the next slowdown. This avoids the brakes as much as possible. I even counted the cars that moved into the gap I created and subtracted when they left my lane. In 1 hour of driving, a total of 11 extra cars got ahead of me. 11 cars in an hour of more relaxed driving adds mere seconds to my commute time while smoothing traffic out for everyone behind me and getting excellent fuel economy.

So you see, for my unusually safe driving technique, a true coast mode makes driving more efficient and less stressful.

The VW Golf EV has something like 4 levels of regen, from pure coasting to 1-pedal driving. Might as well make it an option if it costs nothing to implement.
Last edited by redpoint5 on Tue Aug 15, 2017 5:40 am, edited 1 time in total.

dandrewk
Posts: 239
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Re: Too much regen in D mode

Mon Aug 14, 2017 8:32 pm

PV1 wrote:How long do you usually coast? It's easy to slip into Neutral and truly coast when you want. Hold the shifter forward for a second. To go back to Drive, just click it back.

Just be aware that you have to go back into Drive to get power or regen.


Very bad and potentially dangerous suggestion. The manual clearly advises against using "N" in normal driving conditions.

Besides potentially overheating your brakes, you may run into a situation where you need power -instantly- in order to avoid an accident.

HotPotato
Posts: 29
Joined: Sun Jan 01, 2017 2:08 am

Re: Too much regen in D mode

Tue Aug 15, 2017 5:31 am

dandrewk wrote:
PV1 wrote:How long do you usually coast? It's easy to slip into Neutral and truly coast when you want. Hold the shifter forward for a second. To go back to Drive, just click it back.

Just be aware that you have to go back into Drive to get power or regen.


Very bad and potentially dangerous suggestion. The manual clearly advises against using "N" in normal driving conditions.

Besides potentially overheating your brakes, you may run into a situation where you need power -instantly- in order to avoid an accident.


Operationally, that's no different than coasting in neutral with a manual transmission and popping back into gear if you need acceleration or engine braking. Easier, even: no clutch!

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